Process and device for controlling the electrostatic separation of crude potash salts in electrostatic free fall separators

Claim 1

Process of the electrostatic separation of crushed, chemically conditioned and triboelectrically changed crude potash salt having K 2 O and NaCl constituents, in a free fall electrostatic separator including an upright negative electrode and an upright positive electride for generating the electrostatic field therebetween, and two flow splitting blades pivotably supported below said electrodes and each including a computer controlled drive, said crude potash salt after its passage through the electrostatic field being separated into a valuable substance concentrate accumulating below the lower end of the positive electrode, a residue accumulating below the lower end of the negative electrode, and a middling component whose free fall is substantially unaffected by the electrostatic field, comprising the steps of measuring the amount (M A ) of the charged crude potash salt measuring the content (X P ) of K 2 O and the content (W R ) of kieserit in the residue, measuring the the amount (M R ) of the residue, measuring the content (X WR ) of K 2 O in the valuable substance concentrate, measuring the amount (M M ) of the middling component discharged between said blades, and applying the measured data (M A , X R , W R , M R , X WK ) to a process computer which computes from the measured data the amount (M WK ) of the valuable substance concentrate and the content (W A ) of kieseret in the charged crude potash salt, and generates output signals for automatically controlling via said drives the angular position of said flow splitting blades as a function of the measured and computed data so as to obtain a desired separating effect.